"They shall not pass" (French:'Ils ne passeront pas/On ne passe pas';Spanish:'¡No pasarán!') is asloganused to express determination to defend a position against an enemy.

It was most famously used during the Battle of Verdun in World War I by French General Robert Nivelle. It appears on propaganda posters, such as that by Maurice Neumont after the Second Battle of the Marne, which was later adopted on uniform badges by units manning the Maginot Line. Later during the war, it also was used by Romanian soldiers during the Battle of Mărășești (the Romanian translation of the phrase is "Pe aici nu se trece").

It was also used during the Spanish Civil War, this time at the Siege of Madrid by Dolores Ibárruri Gómez, a member of the Communist Party of Spain, in her famous "No Pasarán" speech on 18 July 1936. The leader of the nationalist forces, GeneralísimoFrancisco Franco, upon gaining Madrid, responded to this slogan with "Hemos pasado" ("We have passed").

"¡No pasarán!" was used by British anti-fascists during the October 1936 Battle of Cable Street, and is still used in this context in some political circles.

There march the militiamenWith great valor to the front.They go singing to give their livesLest Franco, the traitor. triumph.The fascists are in the skiesTheir aerial bombs may destroyOur beautiful capital cityBut to Madrid . . . They Shall Not Pass!

They kill women, children, and the elderlyWho are out and about on the streetsThis is the deed of the fascistsWhich will be inscribed in history.Where heroes' blood watered the fieldBeautiful seedlings will flourish.The cannon roars, the earth trembles